The potato cyst nematode, Globodera rostochiensis, is an
important pest of potato. Like other pathogens, plant parasitic
nematodes are presumed to employ effector proteins, secreted into the
apoplast as well as the host cytoplasm, to alter plant cellular
functions and successfully infect their hosts. We have generated a
library of ORFs encoding putative G. rostochiensis putative apoplastic effectors in vectors for expression in planta.
These clones were assessed for morphological and developmental effects
on plants as well as their ability to induce or suppress plant defenses.
Several CLAVATA3/ESR-like proteins induced developmental phenotypes,
whereas predicted cell wall-modifying proteins induced necrosis and
chlorosis, consistent with roles in cell fate alteration and tissue
invasion, respectively. When directed to the apoplast with a signal
peptide, two effectors, an ubiquitin extension protein (GrUBCEP12) and an expansin-like protein (GrEXPB2), suppressed defense responses including NB-LRR signaling induced in the cytoplasm. GrEXPB2
also elicited defense response in species- and sequence-specific
manner. Our results are consistent with the scenario whereby potato cyst
nematodes secrete effectors that modulate host cell fate and metabolism
as well as modifying host cell walls. Furthermore, we show a novel role
for an apoplastic expansin-like protein in suppressing intra-cellular
defense responses.

The beginning and end dates for each internship will be agreed upon between the Faculty and the Intern. Visa processing time will be a determining factor in actual start date. Minimum period is three months. Maximum period is six months.